Typewriter impression control



Dec. 21, 1965 R. F. BETZLER 3,224,547

TYPEWRITER IMPRESSION CONTROL Filed Feb. 4, 1965 \k\\\ RICHARD F BETZLER FIG. 5 ATTORNEY United States Patent 3,224,547 TYPEWRITER IMPRESSION CONTROL Richard F. Betzler, 609 7th Ave., Folsom, Pa. Filed Feb. 4, 1963, Ser. No. 255,963 2 Claims. (Cl. 197183) This invention relates to typewriters, and more particularly to a device which adjust the printing stroke of type bar in order to eliminate or minimize embossment of the typed sheet of the type.

Typewriters are usually provided with a cylindrical platen which is rotatably mounted on a carriage frame. Further provided are type bars, each carrying type at an end portion thereof and mounted for swinging movement toward and away from one or more sheets positioned in front of the platen to effect printing thereon. It should be understood, however, that the invention is not limited to typewriters having a particular kind of type action.

Almost all conventional typewriters have an abutment member fixed or fixedly secured in position in the path of movement of the type bars on their printing stroke. It is the function of the abutment member to arrest each type bar on its printing stroke and thereby eliminate or minimize embossment of the sheet being typed upon. Were it not for the abutment member, the movement of the type bar would be arrested solely by the platen and the paper in front of it, and then only after the type had delivered the full, crushing impact of its printing stroke to the paper. A fixed abutment member works well when no more than a few sheets of paper are positioned in front of the platen.

Frequently in the daily use of a typewriter, however, it is necessary or desirable for many carbon copies of an original typed sheet to be made simultaneously with the original. This is done by interlaying carbon paper between the regular paper sheets to make up the socalled carbon pack. If a large number of carbon copies are to be made at one time, for example, a dozen copies or more, the carbon pack becomes quite thick; and the first or top sheet is spaced the thickness of the carbon pack from the platen, thereby offsetting the beneficial effect of a fixed abutment member. Unless provision is made in this situation to shorten the printing stroke of the type bars, the first sheet and at least part of the carbon pack will be excessively embossed and sometimes penetrated by the type. This results in an unsatisfactory product and a reduction in the useful life of the carbon paper. Therefore, it is a principal object of the present invention to provide a typewriter having means for adjusting the stroke of the type bars to compensate for the thickness of the carbon pack so that clear and unembossed typed sheets can be produced.

According to the present invention, a movable abutment member is provided which is positioned in the path of movement of the type bars to arrest their movement toward the platen on the printing stroke. Further provided is means operatively associated with the abutment member for repositioning the abutment member in the path of type bar movement so that the printing stroke thereof can be shortened as necessary to eliminate or minimize embossment of the matter being typed.

It is a feature of the present invention that it lends itself to simple and low cost construction which is rugged and dependable in operation. Furthermore, it can be readily incorporated in typewriter constructions without requiring any appreciable modification or rearrangement of parts of known dependability.

Various other objects, features and advantages of the invention will appear more fully from the detailed description which follows, taken in connection with the accompanying drawing, forming a part of the present application, and in which:

FIGURE 1 is a fragmentary, perspective view of a construction embodying the invention;

FIGURE 2 is a vertical sectional view of the construction of FIGURE 1, taken fore and aft therethrough;

FIGURE 3 is a perspective view of selected parts from the construction of FIGURE 1 illustrated in separated relation;

FIGURE 4 is a horizontal sectional view taken through the construction of FIGURE 1, with the abutment member in retracted position; and

FIGURE 5 is a view similar to FIGURE 4, but with the abutment member illustrated in an extended position.

Unless otherwise indicated, it may be assumed that the.

various hereinafter mentioned typewriter parts are suitably arranged and supported on the machine frame in conventional manner.

Referring to the drawing somewhat more in detail, there is shown a type bar 10 having type 12 at one end thereof, and being adapted to swing from a normal position in which it rests on a type rest (not shown) into contact with paper resting against and in front of a cylindrical platen 14. The type bar 10 described herein is representative of a multiplicity of type bars on the machine. The other end of the type bar 10, which is opposite the end thereof carrying the type 12, is pivotally mounted on the usual segment wire 16. The segment wire 16 is, in turn, secured to segment 18. Segment 18 serves as supporting means for the type bars 10, and it has guide slots 19 for the respective type bars 10, the pivoted end of each type bar being received in a slot 19. Since the slots 19 are of well known construction, only representative slots are shown in the drawing. The segment 18 may be shifted up and down relative to the platen 14 to print either upper or lower case letters, but this does not change the length of the printing stroke.

The platen 14. is mounted on a shaft for rotation about a horizontal axis lying in a vertical plane. Rotation of the platen 14, clockwise as viewed in FIGURE 2, moves paper carried thereon upwardly so that successive lines may be typed one below the other. The vertical plane containing the rotational axis of the platen 14 is in parallel relation to another vertical plane passing through the segment wire 16 and the pivotal axes of the. type bars 10; and the structural arrangement of the machine is such that the horizontal distance between these vertical planes remains fixed.

The segment 18 has secured thereto the usual type guide 20 which serves to guide the type bars 10 as each completes a printing stroke. The type guide 20 slidably supports a ribbon holder 22 for vertical movement. Suitable securing means, such as screws 24, are employed to fasten the type guide 20 to an upright wall section 25 of the segment 18.

A scale 26, shown only in FIGURE 1, is provided to aid the operator in arranging and aligning matter to be typed on the sheet carried on the platen 14.

According to the invention, an abutment member 28 is provided which is resiliently and movably mounted on the upright wall section of the segment 18. It is the function of the abutment member 28 to adjust the printing stroke of the type bars 10 so as to eliminate or minimize embossment of the sheets being typed. Preferably, the abutment member 28 is of arcuate shape; and it is mounted on the side of the segment wall section 25 having a surface facing away from the platen 14. As shown in FIGURE 1, the abutment member in retracted position is disposed between the lower portion of the type guide 20 and the upper portion of the segment slots 19.

The manner in which a type bar 10 engages the abut 3 ment member 28 on a printing stroke is illustrated in FIGURE 2, in which view the abutment member is in retracted position and engages the forwardly facing surface of the segment wall section 25. Also, the type face is in engagement with the platen 14, and a rearwardly projecting surface 32 intermediate the ends of the type bar is in engagement with the abutment member 28 so that further movement of the type bar toward the platen is prevented. In normal operation, the type bar 10 rebounds from the abutment member 28 and is returned to rest position immediately after the paper positioned in front of the platen has been struck by the type 12.

Referring now to FIGURES 3, 4 and 5, the abutment member 28 and the means for mounting it will be described in detail. Extending rearwardly from the rear surface of the abutment member 28 are a plurality of lugs, preferably three, as shown, designated by the numerals 34, 36 and 38. These lugs may be of circular cross section; and they extend through matching holes in the segment wall section 25 and terminate an appreciable distance beyond the rear surface thereof. Between each of the lugs 34, 36 and 38 and its associated hole is a free sliding fit which provides guidance during horizontal movement of the abutment member 28.

The end portion of each lug has an annular groove formed therein which is adapted to receive a grip washer or spring clip 44. The latter serves to secure the abutment member 28 against the wall section 25, yet it provides freedom of motion therebetween because the distance between the rear surface of the abutment member and the spring clip 44 appreciably exceeds the thickness of the wall section 25 by the amount of motion to be permitted. Helical compression springs 46 are interposed between each spring clip 44 and the wall section 25, as shown, so that the abutment member 28 will be biased rearwardly into normal engagement with the front surface of the segment wall section 25. Thus, the abutment member 28 is effective to prevent excessive embossrnent, in this fully retracted position, if one sheet or a very thin pack of paper is positioned in front of the platen 14.

With this arrangement, the abutment member 28 is movable, by an applied force, in forward direction away from the front surface of the wall section 25. However, when the applied force is removed, the abutment member will be urged rearwardly by the bias of the springs 46 into normal, retracted position wherein it engages the wall section 25. Stated another way, the springs 46 yieldingly resist movement of the abutment member 28 away from the front surface of the segment wall section 25.

A camming device 50 is provided to move the abutment member 28 forwardly, against the bias of the springs 46. The camming device is operatively associated with the abutment member 28 to position or reposition the member 28 in the path of movement of the type bar 10. In all positions of the abutment member 28 it lies in the path of movement of the projecting surface of the type bar 10. Hence, the further the abutment member is moved away from the wall section 25, the shorter will be the printing stroke of the type bar 10.

The camming device 50 comprises a pair of upright camming legs 52, each having a bifurcated lower end portion making a sliding, pivotal connection with a shoulder stud 54 at the rear of segment 18, as can be seen in FIGURE 2. The upper end of each camming leg 52 is pivotally connected, as by a rivet, to a cross bar 56. The latter extends horizontally, and transversely of the machine; and it is maintained in this general attitude even during transverse movement by vertically extending shoulder screws 58 which pass through horizontally elongated slots 60 in opposite ends of the cross bar 56. The shoulder screws 58 make a tight threaded connection with the segment 18, and the heads thereof are larger than the slots 60 so as to hold the cross bar 56 into slidably free engagement with upper horizontal surfaces of the segment 18 lying on opposite sides of the type guide 20. As shown in FIGURES 1 and 3, the right hand end of the cross bar 56 is turned up and knurled to provide a finger grip 62 by which the cross bar 56 may be manually moved from side to side. During transverse movement of the cross bar 56 the entire camming device 50 moves like a four-bar linkage, with the camming legs 52 being maintained parallel to each other but at various angular inclinations to the horizontal cross bar 56. In order to limit the extent to which the cross bar 56 may be moved in transverse direction the slots 60 are relatively short, being elongated in transverse direction as shown a distance approximately equal to the width of the camming legs 52.

It is the function of the camming legs 52 to move the abutment member 28 forwardly, against the bias of the springs 46, away from the segment wall section 25, so as to reposition the abutment member in the path of movement of the type bar 10. To this end, the camming legs 52 each taper to the left, as viewed in FIGURES 3, 4 and 5, with one leg being maintained in contact with the rear end of lug 34 and the other leg being maintained in contact with the rear end of lug 38. Thus, the rear end surfaces of lugs 34 and 38 serve as follower surfaces, and the forwardly facing surfaces of legs 52 serve as camming surfaces. The thickness of the right edge of each camming leg exceeds the thickness of the left edge thereof by the amount it is desired to move the abutment member 28 from its retracted position shown in FIG- URE 4 to its fully extended position shown in FIGURE 5. An the change in positions of the camming legs 52 with respect to their associated lugs 34 and 38 illustrated in FIGURES 4 and 5 shows how leftward movement of the cross bar 56 effects a camming action which shifts the position of the abutment member 28.

Although the abutment member 28 has been shown in the drawing in only two extreme positions, the full retracted position of FIGURE 4 and the fully extended position of FIGURE 5, it should be understood that it is possible to move the abutment member to various intermediate positions. To this end, and to secure the abutment member 28 in various positions, the right-hand upper horizontal surface of the segment 18 is notched and a resilient detent member 66 is secured to the underside of the right-hand end of the cross bar 56 for cooperating action with the notches 68. With this arrangement, the detent member 66 and the notch 68 it engages cooperate to secure the cross bar 56 against unintentional transverse movement, and it also holds the abutment member 28 from unintentional movement. However, manual movement of the cross bar 56 will shift the detent 66 into engagement with another notch 68, and at the same time the abutment member 28 will be repositioned.

For the convenience of the operator, a pointer 70 is provided on the cross bar 56 for cooperation with indicia 72 inscribed on the segment 18. The pointer 70 will be set to a position on the indicia 72 which corresponds to the desired length of printing stroke of the type bar 10.

Thus, with the aid of the pointer 70 and the indicia 72, the operator is better able to duplicate past successes in adjusting the stroke of the type bar to suit the thickness of the carbon pack. The thicker the carbon pack, the farther to the left the cross bar 56 must be shifted to effect forward repositioning of the abutment member28 and a consequent reduction or elimination of embossment of the copy.

It is a feature of the present invention that the abutment member 28 and camming device 50 provide a positive stop for arresting movement of the type bar as aforesaid. The springs 46 employed herein serve only as return springs and hold the lugs 34 and 38 in engagement with the camming legs 52 by biasing them rearwardly;

The springs 46 do not actually resist or receive the striking force of the type bars, or any part thereof. striking force is received mainly by the abutment mem- Such parts, they all will hold position when the type bars are in action.

From the foregoing it can be seen that an improved typewriter has been provided in which the printing stroke of a type bar can be adjusted to eliminate or minimize embossment of the paper being directly typed upon, even when a thick carbon pack is positioned in front of the platen. The improvement described herein is of simple and economical construction, and yet it is rugged and dependable. The repositioning of the abutment member to a more forward position lets it take more of the impact of the type bar than it would take in a retracted position, and the printing stroke of the type bar is shortened so that the type does not cut through the frontal portion of the carbon pack.

Although the invention has been shown in but one form, it will be obvious to those skilled in the art that it is not so limited, but it is susceptible of various changes and modifications without departing from the spirit thereof.

What is claimed is:

1. In a typewriter, a cylindrical platen mounted for rotation about a fixed horizontal axis, said axis lying in a vertical plane, a type bar, means supporting said type bar for swinging movement toward and away from said platen, an abutment member positioned in the path of movement of said type bar to limit the extent of movement of said type bar toward said platen, said abutment member being resiliently mounted on said supporting means for movement in horizontal direction normal to said vertical plane, said supporting means including an upright surface facing away from said plane and being disposed between said abutment member and said vertical plane, means biasing said abutment member toward said surface, and positioning means movable in a direction parallel to said plane for moving said abutment member against the bias of said biasing means away from said surface to position said abutment member in spaced relation to said supporting means and thereby reduce the extent to which said type bar is movable toward said platen.

2. The combination in a typewriter according to claim 1 wherein the positioning means is manually movable and has camming surfaces, the abutment member has follower surfaces, and said camming surfaces and said follower surfaces are operatively associated.

References Cited by the Examiner UNITED STATES PATENTS 1,177,020 3/1916 Corcoran 197-183 3,018,871 l/1962 Baker 197180 3,095,079 6/1963 Morelli et a1. 197-183 FOREIGN PATENTS 981,231 1/1951 France.

ROBERT E. PULFREY, Primary Examiner. 

1. IN A TYPEWRITER, A CYLINDRICAL PLATEN MOUNTED FOR ROTATION ABOUT A FIXED HORIZONTAL AXIS, SAID AXIS LYING IN A VERTICAL PLANE, A TYPE BAR, MEANS SUPPORTING SAID TYPE BAR FOR SWINGING MOVEMENT TOWARD AND AWAY FROM SAID PLATEN, AN ABUTMENT MEMBER POSITIONED IN THE PATH OF MOVEMENT OF SAID TYPE BAR TO LIMIT THE EXTENT OF MOVEMENT OF SAID TYPE BAR TOWARD SAID PLATEN, SAID ABUTMENT MEMBER BEING RESILIENTLY MOUNTED ON SAID SUPPORTING MEANS FOR MOVEMENT IN HORIZONTAL DIRECTION NORMAL TO SAID VERTICAL PLANE, SAID SUPPORTING MEANS INCLUDING THE UPRIGHT SURFACE FACING AWAY FROM SAID PLANE AND BEING DISPOSED BETWEEN SAID ABUTMENT MEMBER AND SAID VERTICAL PLANE, MEANS BIASING SAID ABUTMENT MEMBER TOWARD SAID SURFACE, AND POSITIONING MEANS MNOVABLE IN A DIRECTION PARALLEL TO SAID PLANE FOR MOVING SAID ABUTMENT MEMBER AGAINST THE BIAS OF SAID BIASING MEANS AWAY FROM SAID SURFACE TO POSITION SAID ABUTMENT MEMBER IN SPACED RELATION TO SAID SUPPORTING MEANS AND THEREBY REDUCE THE EXTENT TO WHICH SAID TYPE BAR IS MOVABLE TOWARD SAID PLATEN. 